Device and method for determining the presence, absence, and/or movement of an object contained in a housing

ABSTRACT

A method for detecting an object in a housing, includes: determining a first scene inside the housing using a time of flight sensor, wherein the housing is empty during determination of the first scene; determining, by a processor, a second scene inside the housing using the time of flight sensor; comparing, by the processor, the first scene with the second scene; and determining, by the processor, a presence or an absence of the object in the housing based on a result of comparing the first scene with the second scene.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to French Patent Application No.1757921, filed on August 28, 2017, which application is herebyincorporated herein by reference.

TECHNICAL FIELD

This disclosure relates generally to the detection of the presence ofone or more objects in a space, and in particular embodiments, to adevice and method for determining the presence, absence, and/or movementof an object contained in a housing.

BACKGROUND

Certain situations make it necessary to determine whether an object ofarbitrary shape, color and construction is present in a housing and/orhas been added or removed from the said housing, for example a devicefor delivering objects storing the objects to be delivered in a box, andwhose recipient removes the objects from the box. It is necessary todetermine, on the one hand, whether all of the objects contained in thebox have been removed or only some of the objects, and, on the otherhand, whether the recipient has added an object to the box.

FIG. 1 illustrates an example of such a delivery device.

FIG. 1 illustrates that the delivery device includes a box 1 furnishedwith a door 2 having a handle. The box 1 includes a presence detectionsensor 3 which determines whether objects ₄ of shape, color andconstructed of materials which differ are contained in the box 1.

The presence detection sensor 3 known from the prior art is for examplean infrared detection device, an ultrasound-based detection device, aninductive or capacitive detection device, a radio identification deviceknown by the acronym RFID (“Radio Frequency Identification”) or a visualdetection device including a camera.

However, the effectiveness of the presence detection devices known fromthe prior art depends in respect of certain devices on the color of theobjects to be detected, in respect of other devices on the materialsconstituting the objects. Moreover, certain devices known from the priorart do not make it possible to determine whether an object was displacedin a housing, nor the degree of occupancy by the objects of themonitored housing. These limitations are well known to the personskilled in the art.

RFID detection devices require that each object be equipped with an RFIDchip, and visual detection devices implement expensive cameras andobject visual recognition algorithms that are complex. These two typesof detection device have significant energy consumption and requiresignificant financial investment.

Consequently, a need exists to produce a device for detecting presencein a given housing of one or more objects of any shape, color andconstruction of materials making it possible to determine the degree ofoccupancy of the said housing while curbing the energy consumption ofthe device and the implementation of which is convenient.

A need also exists to determine whether an object is displaced in themonitored housing.

SUMMARY

According to modes of implementation and embodiments, it isadvantageously proposed to use time of flight sensors which measurethree-dimensional scenes contained in a housing in order to determine,by comparing the said scenes, the presence of at least one objectcontained in the housing.

According to one aspect, there is proposed a method for detecting thepresence or the absence of at least one object in a housing. Theproposed method includes: a) a first step during which a sensor offlight time type measures a first three-dimensional scene inside thehousing devoid of any object; b) a second step during which the sensorof flight time type measures a second scene inside the housing; c) acomparison step during which the said first scene is compared with thesecond scene; and d) a step of determining the presence or the absenceof the object in the said housing, on the basis of the result of thesaid comparison.

A three-dimensional scene is for example a three-dimensionalrepresentation of the interior of the housing obtained for examplethrough a distance mesh.

Advantageously, the implementation of the method does not require a stepof calibration prior to the detection of the possible presence of theobject in the housing.

Advantageously, the method can include a repetition of the second stepat a regular interval.

The device operates intermittently, thereby making it possible to reduceits electrical consumption.

According to one mode of implementation, subsequent to a detection ofthe presence of the said object, a second comparison is performedbetween two successive second steps and a possible removal of the objectis determined on the basis of the second comparison.

According to another mode of implementation, the method furthermoreincludes a calculation of the volume occupied by the object in thehousing.

Advantageously, the method furthermore includes a calculation of adegree of occupancy of the said volume.

According to yet another mode of implementation, the method includes areproduction of steps a) to d), set forth above, for a second sensor ofthe flight time type, and a determination of a displacement of theobject inside the housing on the basis of the two determination steps d)respectively associated with the two sensors.

According to another aspect, there is proposed a device for detectingthe presence or the absence of at least one object in a housing. Theproposed device includes: a sensor of flight time type configured tomeasure a first three-dimensional scene and a second scene of thehousing subsequent to the first scene. The proposed device furtherincludes a processor and/or a plurality of circuits configured toexecute a comparison step configured to compare the two scenes; and adetermination step configured to determine the presence or the absenceof the object in the said housing on the basis of the result of thecomparison.

Advantageously, the processor can furthermore execute a timeout stepconfigured to have the sensor repeat the measurement of a scene atregular intervals.

According to another embodiment, the processor further executes a firstcalculation step configured to calculate the volume occupied by the saidobject in the housing.

Preferably, the processor further executes a second calculation stepconfigured to calculate a degree of occupancy of the housing.

According to yet another embodiment, the device furthermore includes asecond sensor of flight time type configured to measure athree-dimensional scene, the determination step being configured todetermine two items of information regarding presence of the object onthe basis of three-dimensional scenes respectively measured by the twosensors, and a further determination step configured to determine adisplacement of the object inside the housing on the basis of the twoitems of presence information respectively associated with the twosensors.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages and characteristics of the invention will becomeapparent on examining the detailed description of wholly non-limitingembodiments and the appended drawings in which:

FIG. 1 illustrates a device for detecting presence of objects in adefined volume according to the prior art; and

FIGS. 2 to 6 illustrate various embodiments and modes of implementationof the invention.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

FIG. 2 is referred to, which represents an exemplary embodiment of adevice 5 for detecting presence of at least one object 9 of uniformheight H9 and of uniform width L9 in a housing of cubic shape 8 of knowncapacity.

Here, object is understood to mean a solid thing.

Of course the disclosure is not limited to a housing of cubic shape andan object of uniform height and of uniform width, it would be possibleto have a housing of any shape containing one or more objects ofvariable height and/or of variable width.

The device 5 for detecting the presence or the absence of at least oneobject includes a sensor 6 of the flight time type (e.g. time of flightsensor) configured to measure a three-dimensional scene inside thehousing 8 known by the acronym TOF (“Time of Flight”), a processing unit7. The processing unit 7 may implement a comparison step MC configuredto compare two three-dimensional scenes, a determination step MDconfigured to determine the presence or the absence of the object 9 inthe housing 8 on the basis of the result of the comparison, a firstcalculation step MCV configured to calculate the volume occupied by anobject in the housing 8, a timeout step MT configured to repeat themeasurement of a three-dimensional scene by the sensor 6 at regularintervals, a second calculation step MCT configured to calculate thedegree of occupancy T of the housing 8.

The processing unit 7 is embodied for example on the basis of amicroprocessor, but it may be any device able to process the dataprovided by the sensor 6. It may in particular be a microcontroller.

The steps MC, MD, MCV, MT and MCT may be embodied for example insoftware form within a microprocessor, but one may be dealing with anydevice (e.g. digital or analog device) respectively able to compare twothree-dimensional scenes and configured to determine the presence or theabsence of an object in a housing on the basis of the result of thecomparison, able to calculate the volume occupied by an object in thehousing 8, able to have the sensor 6 repeat the measurement of athree-dimensional scene at regular intervals, able to calculate thedegree of occupancy T of the housing.

It may in particular be a microcontroller or a part of the processingunit 7 as represented here.

The sensor 6 of the flight time type gives a three-dimensionalrepresentation of a scene obtained on the basis of a mesh of distances.

For each zone of the mesh, the time of flight sensor TOF measures adistance separating it from an object by measuring a time span Atelapsed between an emission of a signal of the electromagnetic wavetype, such as a laser signal, and the reception of this signal afterreflection on an object present in the field of vision of the sensorTOF.

The sensor 6 is disposed on a first face fi of the housing 8 opposite toa second face f2 of the housing 8 on which the object 9 rests, so thatthe sensor 6 views the face f2. The two faces f1 and f2 are separatedfrom one another by a distance H.

The sensor 6 establishes in real time a three-dimensional scene of theinterior of the housing 8, in particular of the object 9 resting on theface f2.

The distance H9 separates the face f2 and a first end, opposite to theface f2, of the object 9 and a distance Hi separates the face f1 fromthe second end of the object 9 in such a way that the distance H isequal to the sum of the distances H1 and H9.

FIG. 3 illustrates an exemplary implementation of a method for detectingthe presence or the absence of at least one object 9 in the housing 8implementing the device 5. It is implemented by the processing unit 7incorporating the steps MC, MD, MCV, MT, and MCT.

To improve the clarity and the understanding of the exemplaryimplementation of the method, the housing 8 includes a single object 9.

In a first step 1, the housing 8 does not contain any object, that is tosay the housing 8 is empty. The sensor 6 determines a firstthree-dimensional scene S0 including the face f2. As the housing 8 iscubic and the two faces f1 and f2 are separated from one another by thedistance H, the first sensor 6 measures a reference distance H0 of valueequal to the value H for the first scene S0 as a whole. The firstcalculation step MCV determine the value V0 of the empty housing 8 onthe basis of the scene S0 according to methods known to the personskilled in the aft.

Stated otherwise, the time of flight sensor 6 measures a firstthree-dimensional scene So inside the housing 8 devoid of any object.

In a second step 2, the sensor 6 of the flight time type determines asecond scene S1 inside the housing 8.

In step 3, the comparison step MC compares each measurement of distanceof the second three-dimensional scene S1 with the measurements ofdistance of the first scene S0, and then determines the presence or theabsence of the object 9 in the housing 8.

This entails a comparison step during which the said first scene S0 iscompared with the second scene S1 followed by a step of determining thepresence or the absence of the object 9 in the housing 8, on the basisof the result of the comparison.

As long as the housing 8 is empty, the values of distances of the firstscene S0 and of the second scene S1 are equal. The processor 7implementing step MD determines on the basis of the comparison resultsprovided by the comparison step MC whether the housing 8 is empty.

If all the values of the scenes S0 and S1 are equal, that is to say ifthe comparison step MC has not determined any difference between atleast one value of the scene S0 and the corresponding value of the sceneS1, the determination step MD determines that the housing 8 is empty.

If at least one value of the scene S0 the corresponding value of thescene S1 are different, the comparison step MC determines a differencebetween the scenes S0 and S1, and then the determination step MDdetermines that the housing 8 is not empty and contains at least oneobject.

If the housing 8 does not contain any object, the method of FIG. 3returns to step 2.

After a duration t fixed by the timeout step MT, for example 300seconds, a new three-dimensional scene is determined by the sensor 6until the presence of an object in the housing 8 is detected. Statedotherwise, the second step is repeated at a regular interval.

If the housing 8 contains an object (for example the object 9 has beenintroduced into the housing 8), the value of the distances measuredbetween the object 9 and the face 1 of the second scene S1 which aresituated above the surface defined by the projection of the object 9 onthe surface f2, in this instance a rectangle delimited by the distancesL19 and l19, is equal to H1. The comparison step MC determines that thevalue Hi is different from the value H0. The determination step MDdeduces from the difference of the values measured by the sensor 6 thatthe object 9 has been introduced into the housing 8.

If an object has been detected in the housing 8, the method shown inFIG. 3 proceeds to step 4. A third three-dimensional scene S2 isrecorded after the duration t has elapsed reckoning from the end of step3.

In step 5, the values of distances of the first and third scenes S0 andS2 are compared. If the comparison step MC determines that the values ofthe scenes S0 and S2 are equal, the determination step MD deducestherefrom that the object 9 has been removed and the method shown inFIG. 3 returns to step 1.

A second comparison is performed between two successive second steps anda possible removal of the object is determined on the basis of thesecond comparison.

If at least one value of the first scene S0 and the corresponding valueof the third scene S2 are different, as explained previously, thedetermination step MD deduces that at least one object is present in thehousing 8. Stated otherwise, the object 9 is still in the housing 8 orthe object 9 has been removed and another object has been introducedinto the housing 8 or objects have been added into the housing 8.

In step 6, the sensor 6 records a fourth three-dimensional scene S₃after a duration t reckoning from the end of step 5.

As described in step 5, the comparison step MC compares in the followingstep 7 the first scene S0 with the fourth scene S3.

If the determination step MD deduces that the housing 8 is empty, themethod illustrated in FIG. 3 returns to step 1.

If the determination step MD detects the presence of at least one objectin the housing 8, in step 8, the sensor 6 records a fifththree-dimensional scene S₄. On the basis of the scene S₄, the firstcalculation step MCV calculates the value V1 of the housing 8 occupiedby at least one object present in the housing 8.

Stated otherwise, the volume occupied by the said object 9 in the saidhousing 8 is calculated.

Next, the second calculation step MCT determines the degree of occupancyT (expressed as a percentage) of the housing 8 by dividing the volume V1by the volume V0 and multiplying the result obtained by 100.

Stated otherwise, a degree of occupancy T of the said housing 8 iscalculated, and then the method shown in FIG. 3 continues with step 2.

Referring to FIG. 4, which represents an exemplary embodiment of adevice 10 for detecting the presence or the absence and motion of atleast one object in the cubic-shaped housing 8.

The device 10 for detecting presence and motion of an object includesthe sensor 6 and a second sensor 11 identical to the sensor 6 configuredto measure several distances so as to establish in real time athree-dimensional scene (i.e. a distance), a processing unit 12 thatimplements the steps MCV, MT and MCT described previously.

The processing unit 12 is embodied for example on the basis of amicroprocessor, but it may be any device able to process the dataprovided by the sensors 6 and 11. It may in particular be amicrocontroller.

Here, the steps MCV, MT, MCT are incorporated into and/or performed bythe processing unit 12.

The processing unit 12 furthermore executes the determination step MDconfigured to determine two items of information regarding presence ofthe object on the basis of three-dimensional scenes respectivelymeasured by the two sensors 6 and 11.

Furthermore, the processor 12 executes a further determination step MDEPconfigured to determine a displacement of the object 9 inside thehousing 8 on the basis of the two items of presence informationrespectively associated with the two sensors 6 and 11.

The further determination step MDEP can be embodied for example insoftware form within a microprocessor, but one may be dealing with anydevice (e.g. digital or analog device) able to determine a motion of theobject inside the housing on the basis of the results provided by thetwo sensors. It may in particular be a microcontroller or a part of theprocessing unit 12 as represented here.

The further determination step MDEP implements a motion recognitionalgorithm known to the person skilled in the art.

Although the exemplary embodiment describes a housing of cubic shape andan object of uniform height and of uniform width, it would be possibleto have a housing of any shape, and one or more objects of variableheight and/or of variable width.

The sensors 6 and 11 are disposed on the face f1 so that the sensors 6and ii view the face f2. The sensor 11 is disposed at a differentlocation from the sensor 6.

FIG. 5 illustrates an exemplary implementation of a method for detectingthe presence of the object and motion of the object in the housing 8implementing the device 10.

To improve the clarity and the understanding of the implementation ofthe method, the housing 8 includes a single object 9.

In a first step 20, the housing 8 does not contain any object, that isto say the housing 8 is empty. The sensors 6 and 11 each measure a firstthree-dimensional scene respectively S06 and S011 including the face f2.As the housing 8 is of cubic shape and the two faces f1 and f2 areseparated from one another by the distance H, the sensors 6 and 11 eachmeasure a reference distance respectively H06 and H011 of value equal tothe value H for the scenes S06 and S011 together. The first calculationstep MCV determines the value V0 of the volume of the empty housing 8 onthe basis of one of the scenes S06 and S011.

Next in a step 30, the sensors 6 and ii each measure a secondthree-dimensional scene respectively S16 and S111.

In step 40, the motion recognition algorithm implemented by the furtherdetermination step MDEP determines whether an object has moved bycomparing respectively the scenes S06 and S011 with the scenes S16 andS111 recorded by the sensors 6 and 11.

The algorithm determines whether an object has been introduced into thehousing 8.

Stated otherwise, the first step 1, the second step 2 and step 3 arereproduced for a second sensor 11 of flight time type, and adisplacement of the object inside the housing is determined on the basisof the two determination steps respectively associated with the twosensors.

As long as the housing 8 is empty, the values of distances of the scenesS06 and S011 and of the scenes S16 and S111 are equal and the methodshown in Figure ₅ returns to step 30.

After a duration t fixed by the timeout step MT, for example everysecond, the sensors 6 and 11 each measure a three-dimensional sceneuntil the presence of an object in the housing 8 is detected. Statedotherwise, a scene is measured at regular intervals of fixed duration.

If an object has been detected in the housing 8, the method shown inFIG. 5 proceeds to step 50. It is assumed hereinafter that the object 9has been introduced into the housing 8.

The sensors 6 and 11 record a new scene respectively S26 and S211 afterthe duration t has elapsed reckoning from the end of step 40.

Next the further determination step MDEP determine whether the object 9has been removed from the housing 8 or whether an object has been addedinto the housing 8 by comparing respectively the scenes S16 and S111with the scenes S26 and S211.

If the object 9 has not been removed from the housing 8 and no otherobject has been added into the housing 8, the method shown in FIG. 5proceeds to step 8 described previously and thereafter continues withstep 30.

If the object 9 has been removed from the housing 8 or an object hasbeen added into the housing 8, the method shown in FIG. 5 proceeds tostep 60.

The sensors 6 and 11 each measure respectively a scene S36 and S311.

The first calculation step MCV determines the value of the volume V2occupied by the at least one object present in the housing 8.

Next in step 70, the second calculation step MCT determines the degreeof occupancy T1 (expressed as a percentage) of the housing 8 by dividingthe value V2 by the value V0 and multiplying the value obtained by 100.

If the value of T1 is equal to 100%, that is to say the values V0 and V2are equal, the further determination step MDEP deduces that the housing8 is empty and the method shown in FIG. 5 proceeds to step 20.

If the value of T1 is less than 100%, the housing 8 is not empty and themethod shown in FIG. 5 proceeds to step 8.

FIG. 6 illustrates another exemplary embodiment of a time of flightsensor 6 c identical to the sensor 6 including a lens 100 so that thefield of the sensor 6 c covers the whole of the scene F.

Advantageously, only the sensor 6 c is required in order to cover thescene F.

The examples of presence and motion detection devices described operatewhatever the shapes, the colors and the materials of the objects to bedetected, while optimizing the consumption of the devices throughintermittent monitoring.

One or more three-dimensional scenes are recorded by each sensor forexample every 300 seconds. This reduces the electrical consumption ofthe detection devices with respect to the devices of the prior art whichoperate continuously.

The devices operate for any shape of housing to be monitored withoutadjustment step, indeed the initialization step does not depend on theshape of the housing to be monitored.

The ToF sensors exhibit satisfactory measurement precision to 2 m.

What is claimed is:
 1. A method for detecting an object in a housing,the method comprising: determining a first scene inside the housingusing a time of flight sensor, wherein the housing is empty duringdetermination of the first scene; determining, by a processor, a secondscene inside the housing using the time of flight sensor; comparing, bythe processor, the first scene with the second scene; and determining,by the processor, a presence or an absence of the object in the housingbased on a result of comparing the first scene with the second scene. 2.The method according to claim 1, further comprising repeating thedetermining the second scene inside the housing at a regular interval.3. The method according to claim 2, further comprising: determining, bythe processor, that the object is present in the housing; comparing, bythe processor, successive second scenes obtained from repeating thedetermining the second scene inside the housing at the regular interval; and determining, by the processor, whether the object has been removedfrom the housing based on a result of comparing successive secondscenes.
 4. The method according to claim 1, furthermore comprisingdetermining, by the processor, that the object is present in thehousing, and determining, by the processor, a volume occupied by theobject in the housing.
 5. The method according to claim 4, furthermorecomprising determining, by the processor, a degree of occupancy of thehousing.
 6. The method according to claim 1, further comprising:determining a third scene inside the housing using a second time offlight sensor, wherein the housing is empty during determination of thethird scene; determining a fourth scene inside the housing using thesecond time of flight sensor; comparing, by the processor, the thirdscene with the fourth scene; determining, by the processor, the presenceor the absence of the object in the housing based on a result ofcomparing the third scene with the fourth scene; and determining, by theprocessor, a displacement of the object inside the housing based on theresult of comparing the first scene with the second scene and the resultof comparing the third scene with the fourth scene.
 7. The methodaccording to claim 1, wherein each of the first scene and the secondscene comprises a three-dimensional scene.
 8. A device for detecting apresence or an absence of an object in a housing, the device comprising:a time of flight sensor configured to determine a first scene of thehousing and a second scene of the housing subsequent to the first scene;and a processor configured to: compare the first scene with the secondscene; and determine a presence or an absence of the object in thehousing based on a result of comparing the first scene with the secondscene.
 9. The device according to claim 8, wherein the processor isfurther configured to execute a timeout step that causes the time offlight sensor to repeat determinations of the second scene at regularintervals.
 10. The device according to claim 8, wherein the processor isfurther configured to calculate a volume occupied by the object in thehousing.
 11. The device according to claim 10, wherein the processor isfurther configured to calculate a degree of occupancy of the housing.12. The device according to claim 8, wherein the housing is empty duringdetermination of the first scene.
 13. The device according to claim 8,furthermore comprising a second time of flight sensor configured todetermine a third scene and a fourth scene inside the housing.
 14. Thedevice according to claim 13, wherein the processor is furtherconfigured to: compare the third scene with the fourth scene; determinethe presence or the absence of the object in the housing based on aresult of comparing the third scene with the fourth scene; and determinea displacement of the object inside the housing based on the result ofcomparing the first scene with the second scene and the result ofcomparing the third scene with the fourth scene.
 15. The deviceaccording to claim 13, wherein the housing is empty during determinationof the third scene.
 16. The device according to claim 8, wherein each ofthe first scene and the second scene comprises a three-dimensional sceneof contents of the housing.
 17. A device for detecting a presence or anabsence of an object in a housing, the device comprising: a time offlight sensor configured to determine a first scene inside the housing,wherein the housing is empty during determination of the first scene,the time of flight sensor further configured to determine a second sceneinside the housing subsequent to the first scene; a processor; and anon-transistory computer-readable storage medium storing a program to beexecuted by the processor, the program including instructions for:comparing the first scene with the second scene; and determining apresence or an absence of the object in the housing based on a result ofcomparing the first scene with the second scene.
 18. The deviceaccording to claim 17, wherein the program further includes instructionsfor repeating determination of the second scene inside the housing at aregular interval.
 19. The device according to claim 17, wherein theprogram further includes instructions for determining that the object ispresent in the housing, and determining a volume occupied by the objectin the housing.
 20. The device according to claim 17, wherein theprogram further includes instructions for determining a degree ofoccupancy of the housing.